Try an oral flea control like Comfortis. My completely tame cat hates hates hates hates topicals, I have better luck with the topicals on the feral cats than on her! She eats a Comfortis pill like it's a treat. Expensive but very easy. Why fight it? If that's too expensive, try Capstar in a pill pocket or a piece of cheese or hot dog, or whatever this cat can't resist.